Seiko 6602

General question: should the date be adjustable on its own or is the only way to adjust it by sending it around the hours twice for each day ( right now I can’t seem to adjust the date alone)

Looks like Seiko wants 290 to service this watch. The crystal looks a bit worn. A general service I’m sure is in order.
Anyone recommend a 3rd party for this. 290 seems steep.

Thanks in advance